From ba8538e5afb3c46e742f3a31e6046f936777d1a6 2018-10-15 01:27:08
From: Matthias Bussonnier <bussonniermatthias@gmail.com>
Date: 2018-10-15 01:27:08
Subject: [PATCH] Fix to allow entering docstring into IPython.

The EscapeTransformer find method was assuming incorrectly that every
line would end with either a NEWLINE or EOF, while this is not the case
when encountering multiple line string.

This fixes that by making sure we don't index outside of bounds.

With this IPython will correctly add a newline at the CLI.

Closes #11391

---

diff --git a/IPython/core/inputtransformer2.py b/IPython/core/inputtransformer2.py
index 5777559..e2dd2d0 100644
--- a/IPython/core/inputtransformer2.py
+++ b/IPython/core/inputtransformer2.py
@@ -355,9 +355,14 @@ class EscapedCommand(TokenTransformBase):
         """Find the first escaped command (%foo, !foo, etc.) in the cell.
         """
         for line in tokens_by_line:
+            if not line:
+                continue
             ix = 0
-            while line[ix].type in {tokenize.INDENT, tokenize.DEDENT}:
+            ll = len(line)
+            while ll > ix and line[ix].type in {tokenize.INDENT, tokenize.DEDENT}:
                 ix += 1
+            if ix >= ll:
+                continue
             if line[ix].string in ESCAPE_SINGLES:
                 return cls(line[ix].start)
 
diff --git a/IPython/core/tests/test_inputtransformer2.py b/IPython/core/tests/test_inputtransformer2.py
index 6a57b68..d6c2fa3 100644
--- a/IPython/core/tests/test_inputtransformer2.py
+++ b/IPython/core/tests/test_inputtransformer2.py
@@ -233,6 +233,17 @@ def test_check_complete():
         for k in short:
             cc(c+k)
 
+def test_check_complete_II():
+    """
+    Test that multiple line strings are properly handled.
+
+    Separate test function for convenience
+
+    """
+    cc = ipt2.TransformerManager().check_complete
+    nt.assert_equal(cc('''def foo():\n    """'''), ('incomplete', 4))
+
+
 def test_null_cleanup_transformer():
     manager = ipt2.TransformerManager()
     manager.cleanup_transforms.insert(0, null_cleanup_transformer)